Phenomena

Late Ordovician Mass Extinction

Stratigraphy

Citation Formats

General Reference

Earth and Environment Atlas. "Late Ordovician Mass Extinction." Accessed September 9, 2026. https://earth.interactiveatlas.org/phenomena/late-ordovician-mass-extinction.

APA Style

Earth and Environment Atlas. (n.d.). Late Ordovician Mass Extinction. Retrieved September 9, 2026, from https://earth.interactiveatlas.org/phenomena/late-ordovician-mass-extinction

BibTeX

@misc{earthandenvironmentatlas-late-ordovician-mass-extinction,
  author = {Earth and Environment Atlas},
  title = {Late Ordovician Mass Extinction},
  year = {2026},
  url = {https://earth.interactiveatlas.org/phenomena/late-ordovician-mass-extinction},
  note = {Accessed September 9, 2026}
}

The first of the Phanerozoic eon's five major mass extinctions, occurring around 445 million years ago at the boundary between the Ordovician and Silurian periods. Nearly 85 percent of marine species were eliminated in two closely spaced extinction pulses, widely linked to a rapid glaciation and sea level fall followed by expanding ocean anoxia as the ice sheets melted.

Facts

Magnitude or Scale

Nearly 85 percent of marine species eliminated, with an estimated 49 to 60 percent of marine genera lost, across two extinction pulses. 1

Location

Global, with effects concentrated in shallow marine ecosystems. 1

Cross-Tradition Connections